Abstract

From its very beginnings, this century has been under the sign of genetics. Indeed, it was in 1900 that the laws established by Mendel in the mid-nirieteenth century were rediscovered. In that same year, Landsteiner identified the first human blood typing, the ABO system. At that time, agronomists, eugenicists, and physicians were the principal agents of the development of genetics. The chromosome theory of heredity was asserted beginning in 1911; it was followed in the 1940s by the understanding of the role of the gene in cellular metabolism, and in 1954 by the explanation of the structure of the DNA double helix. The pre-eminence of genetics was to increase through the second half of the century, particularly in the 1970s with the advent of genetic engineering.